Although not so limited, this invention has particular reference to the brazing of plate type heat exchangers where plates, spacer elements and extended surface fin means are stacked in an assembled relation and joined together in a furnace brazing, dip brazing or like operation. Preparatory to and during brazing the assembly of heat exchanger parts is held in a fixture, and it is toward improvements in this fixture that the instant invention, in its illustrative embodiment, is directed. Of especial concern are heat exchangers or other assemblies of parts which when assembled have an arcuate or curved configuration.
The purpose of the so-called braze fixture is not only to hold the parts in an assembled relation but to exert a holding pressure which is evenly distributed and uniformly applied. It is the objective to insure that in all affected joints the parts are in continuous contact with one another. In this manner the formation of tight, leak-free joints can reasonably be expected and the heat exchanger made strongly resistant to rupture from internal pressure. Plate type heat exchangers of substantial breadth or length, or both, pose special problems in this regard because of the length of involved joints. The use of relatively heavy flat plates as a part of the braze fixture has been known but these tend to bow when clamped and are not practicably constructed to the necessary precision of dimension. The use of hold down screws, in conjunction with superposing plates, is known but adjustment and readjustment of numerous screws is time consuming and no means exists for obtaining uniformity and continuity of adjustment. Where the assembly of parts to be held has an arcuate or curved form, problems of fixturing are particularly present since means have not heretofore been known for applying a uniform, distributed pressure to such surfaces.